Low pressure process for the hydroconversion of heavy hydrocarbons

ABSTRACT

This invention relates to a process of catalytic hydroconversion of a heavy hydrocarbon oil containing a substantial portion of components having an atmospheric boiling point above 565° C. to give a product hydrocarbon oil containing components having a boiling point below about 565° C. The process includes steps of mixing a heavy hydrocarbon oil with an oil soluble molybdenum compound, introducing the resulting mixture into a hydroconversion zone, introducing a reactor feed gas into the hydroconversion zone, and recovering the product hydrocarbon oil from the hydroconversion zone.

This application claims the benefit of U.S. Provisional Application No.60/011,652, filed on Feb. 14, 1996.

TECHNICAL FIELD OF THE INVENTION

The present invention is generally directed to an improved process forthe hydroconversion or hydrocracking of heavy hydrocarbon oilfeedstocks, heavy whole petroleum crude and heavy refinery residues. Astable process is achieved at reduced pressure by the inclusion of anoil soluble Group VI-B metal compound in the reactor feed. The processis preferably conducted at a total reactor pressure no greater thanabout 13,200 kPa (1900 psig) and preferably from about 9065 kPa (1300psig) to about 11,822 kPa (1700 psig).

BACKGROUND INFORMATION

It is generally desired in the petroleum industry to convert heavyhydrocarbon oil, that is petroleum fractions having an atmosphericboiling point above about 565° C. (1050° F.), into lighter hydrocarbonswhich have higher economic value. In addition, the petroleum industrycontinues to desire a process that can convert heavy whole petroleumcrude oil to lighter crude oil which has a substantially reduced amountof heavy hydrocarbon oil content. Other advantages sought through thetreatment of heavy hydrocarbon oil, heavy whole petroleum crude oil andother similar feeds, particularly high boiling petroleum refineryresidues, include hydrodesulfurization (HDS), hydrogenitrogenation(HDN), carbon residue reduction (CRR), hydrodemetallation (HDM) andsediment reduction.

Hydroconversion processes, also known and referred to herein ashydrocracking, achieve the above noted goals by reacting the feed oilwith hydrogen gas in the presence of a heterogeneous transition metalcatalyst. The heterogeneous transition metal catalyst is typicallysupported on high surface area refractory oxides such as alumina,silica, alumino-silicates, and others which should be known to oneskilled in the art. Such catalyst supports have complex surface porestructure which may include pores that are relatively small in diameter(i.e. micropores) and pores that are relatively large in diameter (i.e.macropores) which effect the reaction characteristics of the catalyst. Aconsiderable amount of research into changing the properties ofhydroconversion catalysts by modifying the pore sizes, pore sizedistribution, pore size ratios and other aspects of the catalyst surfacehas resulted in the achievement of many of the aforementioned goals ofhydroconversion.

An excellent example of such achievements is disclosed in U.S. Pat. No.5,435,908 Nelson et al. in which a supported catalyst achieves goodlevels of hydroconversion of heavy hydrocarbon feeds to products havingan atmospheric boiling point less than 538° C. (1000° F.).Simultaneously, the catalyst and process disclosed produces a liquidhaving an atmospheric boiling point greater than 343° C. (650° F.) witha low sediment content and a product having an atmospheric boiling pointgreater than 538° C. (1000° F.) having a low sulfur content. Thecatalyst includes a Group VIII non-noble metal oxide and a Group VI-Bmetal oxide supported on alumina. The alumina support is characterizedas having a total Surface Area of 150-240 m² /g, a Total Pore volume(TPV) of 0.7 to 0.98, and a Pore Diameter Distribution in which ≦20% ofthe TPV is present as primary micropores having diameters less than orequal to 100 Å, at least about 34% of the TPV is present as secondarymicropores having diameters from about 100 Å to 200 Å and about 26% to46% of the TPV is present as macropores having diameters greater than200 Å.

Another method to substantially achieve some of the above noted goals ofthe hydroconversion of heavy oil feeds is disclosed in U.S. Pat. No.5,108,581 Aldrich et al. As is disclosed by this reference, adispersible or decomposable catalyst precursor along with hydrogen gas,preferably containing hydrogen sulfide, is added to the heavy oil feedand the mixture heated under pressure to form a catalyst concentrate.This catalyst concentrate is then added to the bulk of the heavy oilfeed which is introduced into a hydroconversion reactor. Suitableconditions for the formation of the catalyst concentration includetemperatures of at least 260° C. (500° F.) and elevated pressure from170 kPa (10 psig) to 13,890 kPa (2000 psig) with exemplary conditionsbeing 380° C. (716° F.) and 9,754 kPa (1400 psig). As is taught by thedisclosure, the goal of such conditions is to decompose the catalystprecursor so as to form solid catalyst particles dispersed in thehydrocarbon oil of the catalyst concentrate before it is mixed with thebulk of the heavy feed oil in the hydroconversion reactor.

Despite such advances, the hydroconversion process of heavy hydrocarbonoil requires elevated reactor temperatures (e.g. greater than 315° C.(600° F.)) and high pressures (e.g. above 13,890 kPa (2000 psig)) ofhydrogen containing gas. Due to the combination of elevated temperatureand high pressures of hydrogen gas, the costs of building and operatinga hydroconversion reactor are considerable. One way to reduce thesecosts and to improve safety of the reactor is to lower the reactorpressure. It is well known in the art that operating a hydroconversionreaction at pressures below 13,890 kPa (2000 psig)) causes the formationof intractable residues in the reactor and high levels of sediment inthe product stream. The collection of residues and other sediments inthe reactor and other process systems creates reactor conditions thatare unpredictable and unstable. If this is to be avoided, frequentreactor shutdown and cleaning is required which causes loss ofproduction because the reactor is not "on-line". Clearly unstable andunpredictable reaction conditions are not desirable from a productquality point of view, from a reactor operations point of view or moreimportantly from a safety point of view. Thus there remains an unmetneed in the petroleum industry for a stable hydroconversion process forheavy hydrocarbon oil, heavy whole petroleum crude and heavy refineryresidues that yield lighter hydrocarbons under pressure below 13,890 kPa(2000 psig).

DISCLOSURE OF THE INVENTION

The present invention is generally directed to an improved process forthe hydroconversion or hydrocracking of heavy hydrocarbon oilfeedstocks, heavy whole petroleum crude and other heavy refineryresidues.

In the following disclosure, it should be understood that unless notedotherwise all boiling point values are measured at atmospheric pressure.

It is a particular feature of this invention that it permits operationto be carried out under conditions which yield a substantially decreasedcontent of sediment in the product stream leaving the hydroconversionzone.

The charge to a hydroconversion process is typically characterized by avery low sediment content of 0.01 weight percent (wt %) maximum.Sediment is typically measured by testing a sample by the Shell HotFiltration Solids Test (SHFST). See Jour. Inst. Pet. (1951) 37 pages596-604 Van Kerknoort et al. incorporated herein by reference. Typicalhydroprocessing processes in the art commonly yield Shell Hot FiltrationSolids of above about 0.17 wt % and as high as about 1 wt % in the 343°C.+ (650° F.+) product recovered from the bottoms flash drum (BFD).Production of large amounts of sediment is undesirable in that itresults in deposition in downstream units which in due course must beremoved. This of course requires that the unit be shut down for anundesirable long period of time. Sediment is also undesirable in theproducts because it deposits on and inside various pieces of equipmentdownstream of the hydroprocessing unit and interferes with properfunctioning of e.g. pumps, heat exchangers, fractionating tower, etc.

Very high levels of sediment formation (e.g., 1 wt % in the 343° C.+(65° F.+) portion of the hydroprocessed product), however, are notexperienced by those refiners who operate vacuum resid hydroprocessingunits at stable, moderate conversion levels of feedstock componentshaving boiling points greater than 538° C. (1000° F.) into productshaving boiling points less than 538% (1000% F.) (say, 40-65 volumepercent--vol %--conversion).

In the instant invention the IP 375/86 test method for the determinationof total sediment has been very useful. The test method is described inASTM Designation D 4870-92-incorporated herein by reference. The IP375/86 method was designed for the determination of total sediment inresidual fuels and is very suitable for the determination of totalsediment in our 343° C.+ (650° F.+) boiling point product. The 343° C.+(650° F.+) boiling point product can be directly tested for totalsediment which is designated as the "Existent IP Sediment value." Wehave found that the Existent IP Sediment Test gives essentiallyequivalent test results as the Shell Hot Filtration Solids Testdescribed above.

As it is recommended that the IP 375/86 test method be restricted tosamples containing less than or equal to about 0.4 to 0.5 wt % sediment,we reduce sample size when high sediment values are observed. This leadsto fairly reproducible values for even those samples with very largesediment contents.

As the term is used herein a heavy hydrocarbon oil is a hydrocarbon oilcontaining a substantial amount of components having a boiling pointabove about 565° C. (1050° F.). Heavy hydrocarbon oils which may beutilized in the process of this invention may include high boilingpetroleum cuts typified by gas oils, vacuum gas oils, coal/oil mixtures,residual oils, vacuum residue, and other similar refining residues thathave a high atmospheric boiling point. An illustrative example of such aheavy hydrocarbon oil is an Arabian Medium/Heavy Vacuum Residue havingthe properties set forth in the first column of Table 1. Anotherillustrative example of a heavy hydrocarbon oil includes a mixture of afluid cracked heavy cycle gas oil (FC HCGO) and an Arabian Medium/HeavyVacuum residue the properties of which are given in the second column ofTable 1.

                  TABLE 1                                                         ______________________________________                                        Property           I       II                                                 ______________________________________                                        API Gravity        4.4     3.1                                                  1000° F.+, vol % 87.3 76.1                                             1000° F.+, w % 88.3 --                                                 1000° F.- w % 11.7 --                                                  Sulfur, w % 5.8 5.6                                                           Total Nitrogen, wppm 4815 4328                                                Hydrogen, w % 10.10 9.88                                                      Carbon, w % 83.5 84.10                                                        Alcor MCR, w % 22.4 20.2                                                      Kinematic Viscosity, cSt                                                      @ 200° F. 1706 --                                                      @ 250° F. 476 --                                                       Pour Point, ° F. 110 --                                                n-C.sub.5 Insolubles, w % 35.6 30.16                                          n-C.sub.7 Insolubles, w % 10.97 9.49                                          Toluene Insolubles, w % 0.01 0.01                                             Asphaltenes, w % 10.96 9.48                                                   Metals, wppm                                                                  Ni 44 37                                                                      V 141 118                                                                     Fe 11 9                                                                       Sediment, wppm Nil Nil                                                      ______________________________________                                    

As the term is used herein, a heavy whole petroleum crude oil is adewatered crude oil containing a substantial amount of components havinga boiling point above about 565° C. (1050° F.). An example of heavywhole petroleum crude oil is Middle Eastern heavy whole petroleum crudeoil some of the properties of which are summarized in Table 2 and thedistillation data for which is given in Table 3.

                  TABLE 2                                                         ______________________________________                                        Property                                                                      ______________________________________                                        API Gravity            14.4                                                     Sulfur (w %) 6.17                                                             Total Nitrogen (wppm) 2255                                                    Pour Point (° C. (F. °)) -25 (-14)                              Viscosity (cst) @ 20° C. 2045.0                                        @ 40° C. 429.1                                                         @ 50° C. 229.0                                                         Neutralization Number (mg KOH/gm) 0.55                                        Microcarbon Residue (w %) 12.6                                                Vanadium (wppm) 68                                                            Nickel (wppm) 29                                                              Iron (wppm) 9                                                                 C.sub.6 's and heavier (LV %) 99.82                                         ______________________________________                                    

                  TABLE 3                                                         ______________________________________                                        Fraction      Boiling Range (° C. (F. °))                                                     Weight %                                        ______________________________________                                        Light Hydrocarbons                                                                          IBP to C4       0.1                                               Light Naptha iC5 to 82 (180) 0.2                                              Intermediate Naptha 82 (180) to 130 (265) 0.9                                 Heavy Naptha 130 (265) to 177 (350) 2.2                                       Light Kerosene 177 (350) to 218 (425) 3.5                                     Heavy Kerosene 218 (425) to 260 (500) 4.4                                     Atmospheric Gas Oil 260 (500) to 343 (650) 11.5                               Light Vacuum Gas Oil 343 (650) to 454 (850) 18.4                              Heavy Vacuum Gas Oil 454 (850) to 566 (1050) 17.2                             Vacuum Residue 566 (1050) and greater 41.6                                  ______________________________________                                    

The process of this invention is also useful for the hydroconversion ofother refinery residues and high boiling oils which contain a majorityof components boiling above 565° C. (1050° F.) thus converting them tohydrocarbon products boiling below 565° C. (1050° F.). In such cases thereactor feed may be Bottoms Flash Drum liquids which have a nominal 343°C.+ (650° F.+ boiling point, coal/oil mixtures, tar sand extracts,bottoms from deasphalting processes and other similar hydrocarbonmixtures having a boiling point of above 343° C. (650° F.). Such liquidscan be generally characterized as also having undesirably high contentof components boiling above 565° C. (1050° F.), sediment-formers, a highcontent of metals, a high sulfur content, carbon residue, andasphaltenes. Asphaltenes are herein defined as the quantity of n-heptaneinsolubles minus the quantity of toluene insolubles in the feedstock orproduct.

The present invention may be carried out in any hydroconversion zonesuitable for the conditions of the improved hydroconversion reaction asis described herein. For the purposes of the present disclosure, ahydroconversion zone can be accomplished by either a slurry technique orby an expanded bed technique, also know as an ebullated bed technique.If an ebullated bed technique is used, the hydroconversion zone maycontain one or more reactors which contain expanded beds of supportedheterogeneous catalyst. Generally in an ebullated bed process, the bedof supported catalyst is expanded and modified by upflow of the liquidfeed and hydrogen containing feed gas in the reactor at space velocitieseffective to provide adequate mobilization and expansion of thecatalyst. Thus contact between the catalyst and the reactants ispromoted without substantial carry over of the supported catalyst intothe product stream. The bulk density of the supported catalyst is afactor in the selection of the catalyst from the stand point ofattaining appropriate bed expansion and mobilization at effective spacevelocities. In practice of the process of this invention, the catalyst,preferably in the form of extruded cylinders of about 0.030 to 0.050inch diameter and about 0.08 to 0.15 inch length may be placed within areactor in an amount sufficient to occupy at least about 30% of thereactor void volume. Catalyst is typically withdrawn on a periodic basisand then replaced with new catalyst to maintain the proper amount ofcatalyst present and maintain constant catalyst activity in the reactor.Specific details of ebullated bed reactors should be known to oneskilled in the art as exemplified by U.S. Pat. Nos. 4,549,957;3,188,286; 3,630,887; 2,987,465; and Re. 25,770 the contents of whichare hereby incorporated herein by reference.

The heterogeneous catalyst utilized in the process of the presentinvention is disclosed in detail in U.S. Pat. No. 5,435,908 the contentsof which are hereby incorporated herein by reference. The catalystsupport may be alumina, silica, alumino-silicates or any otherconventional heterogeneous catalyst support which should be known to oneskilled in the art. As is disclosed therein, alumina is the preferredsupport and may be alpha, beta, theta, or gamma alumina, although it ispreferred to use gamma alumina. The catalyst which may be employedshould be selected and characterized based on the properties of TotalSurface Area (TSA), Total Pore Volume (TPV), and Pore DiameterDistribution (Pore Size Distribution PSD). The Total Surface Area shouldbe about 150-240, preferably about 165-210. The Total Pore Volume (TPV)may be about 0.70-0.98, preferably 0.75-0.95.

The Pore Size Distribution (PSD) is such that the substrate containsprimary micropores of diameter less than about 100 Å in amount less than0.20 cc/g and preferably less than about 0.15 cc/g. Although it may bedesired to decrease the volume of these primary micropores to 0 cc/g, inpractice its found that the advantages of this invention may be attainedwhen the volume of the primary micropores is about 0.04-0.16 cc/g. Thiscorresponds to less than about 20% of TPV, preferably less than about18% of TPV. The advantages are particularly attained at about 5-18% ofTPV. It will be apparent that the figures stated for the % of TPV mayvary depending on the actual TPV (in terms of cc/g). Secondarymicropores having diameters in the range of about 100 Å-200 Å arepresent in amount as high as possible and at least about 0.33 cc/g (34%of TPV) and more preferably at least about 0.40 cc/g (50% of TPV).Although it is desirable to have the volume of secondary micropores ashigh as possible (up to about 74%) of the TPV, it is found that theadvantages of this invention may be attained when the volume ofsecondary micropores is about 0.33-0.6 cc/g.

Pores having a diameter greater than 200Å are considered macropores andshould be present in amount of 0.18-0.45 cc/g (26-46% of TPV) whilemacropores having diameters greater than 1000Å are preferably present inamount of about 0.1-0.32 cc/g (14-33% of TPV),.

It will be apparent that the catalysts of this invention are essentiallybimodal: there is one major peak in the secondary micropore region of100 Å-200 Å and a second lesser peak in the macropore region of greaterthan or equal to 200 Å.

The catalyst support which may be employed in practice of this inventionis available commercially from catalyst suppliers or it may be preparedby variety of processes typified by that wherein about 85-90 parts ofpseudobohmite silica-alumina is mixed with about 10-15 parts of recycledfines. Acids is added and the mixture is mulled and then extruded in anAuger type extruder through a die having cylindrical holes sized toyield a calcined substrate of 0.035±0.003 inch diameter. Extrudate isair-dried to a final temperature of typically about 121°-135° C.(250°-275° F.) yielding extrudates with about 20-25% of ignited solids.The air-dried extrudate is then calcined in an indirect fired kiln forabout 0.5-4 hours in an atmosphere of air and steam at typically about538°-621° C. (1000°-1150° F.).

Generally the alumina support and the finished catalysts utilized in theprocess of the present invention should have the characteristics andproperties set forth in Table 4 wherein is should be noted that:

Column 1 lists the broad characteristics for the catalyst supportincluding Pore Volume in cc/g and as % of TPV; Pore Volume occupied bypores falling in designated ranges--as a v % of Total Pore Volume TPV;and the Total Surface Area in m² /g.

Column 2 lists the broad range of characteristics for a First Type ofcatalyst useful in the practice of this invention.

Column 3 lists the characteristics of a catalyst that is illustrative ofa preferred catalyst used in the practice of the present invention.

Column 4 lists a broad range of characteristics for a Second Type ofcatalyst found to be useful in practice of the process of thisinvention.

                  TABLE 4                                                         ______________________________________                                                1       2        3         4                                          ______________________________________                                        TPV (cc/g)                                                                              0.7-0.98  0.7-0.98 0.87    0.7-0.98                                   ≧1000 Å 0.1-0.32 0.1-0.22 0.16 0.15-0.32                           ≧250 Å 0.15-0.42 0.15-0.31 0.26 0.22-0.42                          ≧200 Å 0.18-0.45 0.18-0.34 0.29 0.24-0.45                          ≦100 Å 0.2 max 0.15 max 0.09 0.2 max                               100-200 0.33 min 0.40 min 0.49 0.33 min                                       TPV(%) 100 100 100 100                                                        ≧1000 Å 14-33 14-22 18.4 22-33                                     ≧250 Å 22-43 22-32 29.9 32-43                                      ≧200 Å 26-46 26-35 33.4 35-46                                      ≦100 Å 20 max 15 max 10.3 20 max                                   100-200 Å 34 min 50 min 56.3 34 min                                       Total Surface 150-240 155-240 199 150-210                                     Area (m.sup.2 /g)                                                           ______________________________________                                    

At least a portion of the surface of the catalyst support is coveredwith metals or metal oxides to yield a product catalyst containing aGroup VIII non-noble oxide in amount of 2.2 to 6 weight percent, and aGroup VI-B metal oxide in amount of 7 to 24 weight percent. The GroupVIII metal may be a non-noble metal such as iron, cobalt, or nickel andpreferably is nickel. The Group VI-B metal may be chromium, molybdenum,or tungsten and preferably is molybdenum.

The catalysts utilized in the process of the present invention shouldcontain no more than about 2 weight percent of P₂ O₅ and preferably lessthan about 0.2 weight percent. Phosphorus-containing components shouldnot be intentionally added during catalyst preparation because thepresence of phosphorus undesirably contributes to sediment formation.Silica SiO₂ may be incorporated in small amounts typically up to about2.5 weight percent.

These catalyst metals may be loaded onto the alumina support by sprayingthe support with a solution containing the appropriate amounts of watersoluble metal compounds. The Group VIII metal may be loaded onto thealumina typically from a 10 to 50 weight percent aqueous solution of asuitable water-soluble salt such as nitrate, acetate, oxalate and othersimilarly suitable compounds The Group VI-B metal may be loaded onto thealumina typically from a 10 to 25 weight percent aqueous solution of awater-soluble salt such as ammonium molybdate or other suitablemolybdate salts. Small amounts of H₂ O₂ may be added to stabilize theimpregnating solution. It is preferred that solutions stabilized with H₃PO₄ not be used in order to avoid incorporating phosphorus into thecatalyst. Loading of each metal may be effected by spraying the aluminasupport with the aqueous solution at 15°-38° C. (60°-100° F.) followedby draining, drying at 104°-149° C. (220°-300° F.) for 2-10 hours andcalcining at 482°-677° C. (900°-1250° F.) for 0.5-5 hours.

The heterogeneous catalyst may be characterized by the content of metalsor metal oxides deposited on the at least part of the catalyst supportsurface. Such parameters are given in Table 5. It should be noted thatthe column numbers utilized in this table correspond to those used abovein Table 4.

                  TABLE 5                                                         ______________________________________                                        Metals (w %) 1        2         3      4                                      ______________________________________                                        VIII         2.2-6    2.5-6     3.1    2.2-6                                    VIB 7-24 13-24 14 7-24                                                        SiO.sub.2 <2.5 <2.5 2 <2                                                      P.sub.2 O.sub.5 <2 <2 ≦0.2 <2                                        ______________________________________                                    

In the general practice of the process of this invention, a suitableamount of the heterogeneous catalyst is placed within a reactor. Thefeed mixture is admitted to the lower portion of the reactor which ismaintained at a temperature of about 343°-454° C. (650°-850° F.),preferably about 371° C. (700° F.) to about 441° C. (825° F.). The totalpressure of the reactor may be from about 6996 kPa (1000 psig) to about24,233 kPa (3500 psig) but preferably it is maintained from about 9065kPa (1300 psig) to about 11,822 kPa (1700 psig). The hydrogen containingfeed gas is often admitted mixed with the hydrocarbon charge. Typicallythe hydrogen containing feed gas is introduced at a rate from about356.2 liters (H₂) / liters(oil) (2000 standard cubic feet (H₂) / Barrel(oil)) to about 1781.2 liters (H₂) / liters(oil) (10,000 standard cubicfeet (H₂) / Barrel (oil)) and preferably from about 356.2 liters (H₂) /liters(oil) (2000 standard cubic feet (H₂) / Barrel (oil)) to about712.5 liters (H₂) / liters(oil) (4,000 standard cubic feet (H₂) / Barrel(oil)). In an ebullated bed reactor, the flow of the reaction feedmixture through the bed should be conducted at a rate from about 0.08 to1.5 m³ (oil) / m³ (reactor void volume)/hour and preferably from about0.1 to 1.0 m³ (oil) / m³ (reactor void volume)/hour. During operation,the bed expands to form an ebullated bed with a defined upper level. Thepassage of the hydrocarbon feedstock through the ebullated bed reactorconverts at least a portion of the higher boiling point hydrocarbons tolower boiling products by the hydroconversion/hydrocracking reaction.Recovery of the product hydrocarbon oil which includes a substantialportion of components having a boiling point below about 565° C. (1050°F.) is effected by conventional means from the portion of the reactorabove the upper level of the ebullated bed so that heterogeneouscatalyst is not removed. Further conventional means such as passagethrough a hot separator, cold separator, pressure flash drums,atmospheric and vacuum fractionators and other conventional means allowsfor the separation of the different fraction of the product stream. Inone embodiment, the highest boil fractions of the product stream aredirected back through the hydroconversion zone as part of thehydrocarbon feed. Thus by "recycling" the higher boiling point fractionsof the product back into the reaction a minimal amount of reactor wasteis generated. Operation of the hydroconversion zone is essentiallyisothermal with a typical maximum temperature difference between theinlet and the outlet of about 0° to 27° C. (0°-50° F.), preferably fromabout 0° to 16° C. (0°-30° F.).

It has been unexpectedly and surprisingly found that the inclusion of aGroup VI-B metal compound in the heavy hydrocarbon oil feed achieves astable hydroconversion reaction at total pressures below 13,200 kPa(1900 psig). As previously noted, prior to the present invention,hydroconversion or hydrocracking reactions carried out under suchconditions become unpredictable and unstable due to the accumulation ofdeposits and sediments in the reactor and the relevant process systems.In contrast it has been found that the content of such deposits andsediments are substantially reduced in the practice of the presentinvention. The Group VI-B metal compound should be selected so that thefirst decomposition temperature that is at least 222° C. (431° F.). Thisis substantially greater than the first decompositions temperature ofother molybdenum compounds utilized in the prior art such as molybdenumnaphthalate (166° C. (331° F.)) or molybdenum octoate (111° C. (231°F.)). In addition, the compound should be soluble in the heavyhydrocarbon oil feed utilized in the hydroconversion reaction.

In one embodiment of the present invention the Group VI-B metal compoundis mixed with the heavy hydrocarbon oil to give a mixture having fromabout 0.005 to about 0.050 weight percent metal compound present in thehydroconversion reactor feed mixture. When calculated based on theamount of elemental metal, these concentrations of metal compoundcorrespond to values of 0.001 to about 0.004 weight percent metal.

In another related embodiment the Group VI-B metal is dissolved in aportion of the heavy hydrocarbon oil to give a pre-feed mixture in whichthe concentration of metal compound is from about 0.02 to about 0.42weight percent which corresponds to a concentration of about 0.004 to0.03 of metal when calculated based on the amount of elemental metalpresent. This pre-feed mixture is mixed with additional hydrocarbon oilto give the final reactor feed of the heavy hydrocarbon oil and theGroup VI-B metal compound having from about 0.005 to about 0.050 weightpercent metal compound present which when calculated based on the amountof elemental metal, correspond to values of 0.001 to about 0.004 weightpercent metal.

In yet another embodiment the Group VI-B metal compound is an oilsoluble molybdenum compound. The oil soluble molybdenum compound ismixed with the heavy hydrocarbon oil to give a mixture having from about0.005 to about 0.050 weight percent metal compound present in thehydroconversion reactor feed. These concentrations of metal compoundcorrespond to values of 0.001 to about 0.004 weight percent whencalculated based on elemental molybdenum. A commercially availablemolybdenum compound that has been found to be especially useful in thepractice of the present invention is molybdenum LIN-ALL(TM) which is aproprietary mixture including the reaction products of molybdenum withtall oil fatty acids available from OMG Americas, Inc. of Cleveland,Ohio USA.

Therefore in view of the above, one aspect of the present invention is aprocess of catalytic hydroconversion of a heavy hydrocarbon oilcontaining a substantial portion of components having an atmosphericboiling point above about 565° C. (1050° F.) to give a producthydrocarbon oil containing a substantial portion of components having aboiling point below about 565° C. (1050° F.). The process includesmixing the heavy hydrocarbon oil with an oil soluble molybdenumcompound, to give a mixture having from about 0.005 to about 0.050weight percent molybdenum compound. In one embodiment this may beachieved by mixing a first portion of the heavy hydrocarbon oil with thesoluble molybdenum compound to give a pre-feed mixture in which theconcentration of molybdenum compound is from about 0.02 to about 0.42weight percent, and mixing the pre-feed mixture with additional heavyhydrocarbon oil to give a reactor feed mixture having a concentration ofmolybdenum compound from about 0.005 to about 0.050 weight percent. Themolybdenum compound is selected so that it has a first decompositiontemperature of at least 222° C. (431° F.). The mixture of heavyhydrocarbon oil and molybdenum compound is introduced into ahydroconversion zone having a temperature, from about 343° C. (650° F.)to about 454° C. (850° F.) and a total pressure from about 6996 kPa(1000 psig) to about 24,233 kPa (3500 psig). The hydroconversion zoneshould contain a heterogeneous catalyst which includes a Group VIIInon-noble metal oxide, a Group VI-B metal oxide and no more than 2weight percent phosphorous oxide supported on an alumina orsilica-alumina support. In a sub-embodiment the Group VIII non-noblemetal oxide is nickel and the Group VI-B metal oxide is molybdenum. Inanother sub-embodiment the catalyst support is alumina which has a TotalSurface Area from about 150 to 240 m² /g, a Total Pore Volume (TPV) from0.7 to 0.98 and a pore diameter distribution such that no more than 20%of the TPV is present as primary micropores having diameters no greaterthan 100 Å, at least about 34% of the TPV is present as secondarymicropores having diameters from about 100 to 200 Å, and from about 26%to 46% of the TPV is present as macropores having diameters of at least200 Å. Also being introduced into the hydroconversion zone is a reactorfeed gas which includes a majority of hydrogen gas, preferably at least93% by volume of hydrogen and which is substantially free of hydrogensulfide. The hydrogen containing feed gas is introduced at a rate from356.2 liters (H₂) / liters(oil) (2000 standard cubic feet (H₂) / Barrel(oil)) to about 1781.2 liters (H₂) / liters(oil) (10,000 standard cubicfeet (H₂) / Barrel (oil)). In one sub embodiment of this aspect of thepresent invention the temperature of the hydroconversion zone is fromabout 371° C. (700° F.) to about 441° C. (825° F.) and the totalpressure is from about 9065 kPa (1300 psig) to about 11,822 kPa (1700psig). When the hydroconversion zone is an ebullated bed reactor, theintroduction of the feed mixture into the hydroconversion zone isconducted at a rate from about 0.08 to 1.5 m³ (oil) / m³ (reactor voidvolume)/hour. During the practice of any of the above noted aspects ofthe invention the product hydrocarbon oil is recovered by conventionalmeans from the hydroconversion zone. The recovered product hydrocarbonoil has an API gravity uplift of greater than 10 over the API gravity ofthe heavy hydrocarbon oil feed sediment content. Of particular note, thesediment content of the product fraction that has a boiling point higherthat 343° C. (650° F.) is substantially reduced when compared to thesame product fraction resulting from the practice of the process in theabsence of the molybdenum compound in particular sediment valuesachieved are below 1 weight percent and preferably below 0.7 weightpercent.

Another aspect of the present invention is a method of hydrocracking aheavy whole petroleum crude oil having at least 40 weight percentcomponents boiling above about 565° C. (1050° F.) to give a processedcrude oil containing a majority of components boiling below about 565°C. (1050° F.). The method of this aspect comprises mixing the heavywhole petroleum crude with a oil soluble Group VI-B metal compoundhaving a first decomposition temperature of at least 222° C. (431° F.),to give a reactor feed mixture having from about 0.005 to about 0.050weight percent metal compound; reacting the reactor feed mixture and ahydrogen containing feed gas in an ebullated-bed reactor, and recoveringthe product processed crude oil by conventional means. In this aspectthe reactor is at a temperature from about 343° C. (650° F.) to about454° C. (850° F.) and at a total pressure of no greater than about13,201 kPa (1900 psig). The ebullated bed includes a supportedheterogeneous catalyst, the supported heterogeneous catalyst comprisinga Group VIII non-noble metal oxide, a Group VI-B metal oxide, no morethan 2 weight percent phosphorous oxide and an alumina or silica-aluminasupport. One facet of the present aspect is that the alumina orsilica-alumina support is selected so that the resultant meals bearingcatalyst has a Total Surface Area (TSA) of about 150 to 240 m2/g, andTotal Pore Volume (TPV) from about 0.7 to 0.98 and a pore diameterdistribution such that no more than 20% of the TPV is present as primarymicropores having diameters no greater than 100 Å, at least about 34% ofthe TPV is present as secondary micropores having diameters from about100 Å to about 200 Å, and from about 26% to about 46% of the TPV ispresent as macropores having diameters of at least 200 Å. Within anotherfacet of this aspect of the present invention the Group VI-B metalcompound in the reactor feed mixture is a molybdenum compound may beeither mixed directly into the feed mixture or made by combining a firstportion of the heavy whole petroleum crude oil with the oil solublemolybdenum compound to give a pre-feed mixture in which theconcentration of molybdenum compound is from about 0.020 to about 0.420weight percent, and mixing the pre-feed mixture with additional heavywhole petroleum crude oil to give a reactor feed mixture having aconcentration of molybdenum compound from about 0.005 to about 0.050weight percent. The recovered processed crude oil resulting from thepractice of the present aspect of the invention has an API gravityuplift of greater than 10 over the API gravity of the heavy wholepetroleum crude oil. In addition the processed crude oil has a decreasedamount of sediment in the portion of the processed heavy crude oilhaving a boiling point above about 343° C. (650° F.) as compared withthe same product resulting from the process conducted without themolybdenum compound in the reactor feed mixture.

The following examples are included to demonstrate preferred embodimentsof the invention. It should be appreciated by those of skill in the artthat the techniques disclosed in the examples which follow representtechniques discovered by the inventors to function well in the practiceof the invention, and thus can be considered to constitute preferredmodes for its practice. However, those of skill in the art should, inlight of the present disclosure, appreciate that many changes can bemade in the specific embodiments which are disclosed and still obtain alike or similar result without departing from the scope of theinvention.

In the following examples the heavy hydrocarbon oil feedstock was aMid-Eastern Heavy Whole Crude oil straight out of the ground with noother treatment except dewatering, before introduction to the process ofthe instant invention. Properties of the Mid-Eastern Heavy Whole crudeoil are given above in Tables 2 and 3.

EXAMPLE 1

An ebullated bed pilot unit was charged with heterogeneous catalysthaving the properties of Column 3 in Tables 4 and 5. The heavyhydrocarbon oil feed was admitted in the liquid phase at 2515 psig tothe ebullated bed pilot unit with an overall liquid space velocity(LHSV) of 0.54 per hour and an overall average temperature of 415° C.(780° F.) to maintain the reactor conditions. Hydrogen containing feedgas containing at least 93% by volume hydrogen and substantially free ofhydrogen sulfide is mixed with the oil feed in an amount of 623 liters(H₂) / liters(oil) (3500 standard cubic feet(gas) / barrel (oil)).During the course of the experiment the hydroconversion zone of theebullated bed pilot unit was maintained at a temperature of about 415°C. (780° F.). The through-put ratio for the reaction was about 1.0. Thethrough-put ratio is defined as the ratio of the volumetric reactor feedrate, including recycle, to the volumetric fresh feed rate The totalpressure of the hydroconversion zone was decreased until the reactionbecame unstable.

A sample of the results are given in below in Table 6 along with theproperties of the reaction product from each pilot run. It should benoted that the values for each run were taken approximately seven daysafter the change in total pressure so as to allow the reaction tostabilize. The values for run 3419 are given in brackets because the runat 1700 psig were unstable after the seven day stabilization period.With regard to Table 6 it should be noted that: the values for thechange in the API gravity are relative to the API gravity of thehydrocarbon oil feed; the value for conversion is the percent decreasein the volume of the fraction boiling above 538° C. (1000° F.) of thehydrocarbon feed; the abbreviation BFD refers to the Bottoms Flash Drumfraction of the product hydrocarbon which has a nominal boiling point ofgreater than 343° C. (650° F.) and TLP refers to the Total LiquidProduct recovered from the hydroconversion zone.

                  TABLE 6                                                         ______________________________________                                        Run No.     3407    3411    3413  3416  3419                                  ______________________________________                                        Total Pressure, kPa                                                                       17,338  15,959  14,378                                                                              13,201                                                                              [11,822]                                (psig) (2500) (2300) (2100) (1900) [(1700)]                                   Inlet H.sub.2 Partial 2325 2139 1953 1767 [1581]                              Pressure (psig)                                                               Metered H.sub.2 183 167 158 136 --                                            Consumption,                                                                  1 (H.sub.2)/1 (oil) (1030) (939) (887) (765) --                               (SCF/Bbl)                                                                     Properties of Product                                                         Change in API gravity +12.5 +12.1 +11.8 +10.7 --                              Conversion (vol %) 56.8 57.8 54.9 53.5 --                                     BFD sediment (wt %) 0.13 0.21 0.16 0.23 [1.46]                                TLP sediment (wt %) 0.66 0.93 0.86 1.75 [1.61]                              ______________________________________                                    

Given the above data, one of ordinary skill in the art should noticethat as the pressure of the reaction decreases, the amount of sedimentpresent in both the BFD fraction and the TLP increases. This increase insediment is believed to be due to the incomplete conversion of largemolecular weight hydrocarbons present in the hydrocarbon feed. Oneskilled in the art should also appreciate that the sediment values ofrun 3419 are substantially higher than is typically consideredacceptable in the practice of the hydroconversion process which aretypically below 1.0 weight percent and preferably below 0.7 weightpercent.

The instability of the hydroconversion reaction at 1700 psig totalpressure, as noted above for run 3417 is further supported by the datashown below in Table 7 which gives a detailed look at the sedimentationproblem encountered. With reference to Table 7 it should be noted thatthe values given are for reactions that have "lined-out" that is to saythe parameters have become stable. It should further be noted that: VBRmeans Vacuum Bottoms Recycle which is a process in which the fraction ofthe product stream that has a boil point greater than about 538° C.(1000° F.) is reintroduced into the hydroconversion zone as a portion ofthe hydrocarbon feed. This technique is conventionally used to reducethe sediment content of the hydrocarbon product.

                  TABLE 7                                                         ______________________________________                                        Run No.     3420         3424   3426                                          ______________________________________                                        VBR         Yes          Yes    No                                              BFD Sediment 0.18 2.4 4.1                                                     (wt %)                                                                        TLP Sediment 1.55 1.57 --                                                     (wt %)                                                                      ______________________________________                                    

In view of the above, one skilled in the art should appreciate that thelevel of sediment rapidly increases when the hydroconversion zone isoperated at a total pressure of 11,822 kPa(1700 psig). The use of vacuumbottoms recycling did not reduce the sediment content under thesehydroconversion conditions. Once VBR was stopped the sediment contentrapidly reached unacceptably high levels which is considered an unstablecondition.

EXAMPLE 2

In this example the ebullated bed reactor utilized above in Example 1was used. Molybdenum LIN-ALL(TM) available from OMG Americas, Inc. ofCleveland Ohio USA was mixed and introduced into the hydroconversionzone via the purge oil system through the catalyst withdrawal tube. Theconcentration of the molybdenum compound was about 1500 parts permillion by weight of the purge oil which corresponds to approximately220 parts per million by weight of metal. The purge oil stream washeated to about 200°-250° F. just prior to injection into thehydroconversion zone. The purge oil stream represent 13.6% of the freshfeed going to the unit. As noted in Table 8 below, this is consideredinjection method A. A sample of the properties of the reaction productare given in below in Table 8. It should be noted that the values foreach run were taken approximately seven days after the firstintroduction of molybdenum compound so as to allow the reaction tostabilize.

                  TABLE 8                                                         ______________________________________                                        Run No.          3429     3432     3435                                       ______________________________________                                        Injection Method A        B        B                                            Total Pressure, kPa 11,822                                                    (psig) (1700) (1500) (1300)                                                   Inlet H.sub.2 Partial Pressure 2325 2139 1953                                 (psig)                                                                        Metered H.sub.2 Consumption, 183 167 158                                      1 (H.sub.2)/1 (oil) (SCF/Bbl) (1030) (939) (887)                              Properties of Product                                                         Change in API gravity +10.8 +10.6 +10.2                                       Conversion (vol %) 49.6 50.3 53.5                                             BFD sediment (wt %) 0.29 0.37 0.56                                            TLP sediment (wt %) 0.63 n/a 1.28                                           ______________________________________                                    

In view of the above results one of ordinary skill in the art shouldappreciate that the introduction of the molybdenum compound into thehydroconversion zone substantially reduces the sediment content of thehydrocarbon product stream. It should be appreciated by one of skill inthe art that the sediment values of the product stream have a directeffect on the long term operation of the hydroconversion reactor. Aspreviously noted high BFD sediment values (i.e. above about 1.0 wt %)are undesirable.

EXAMPLE 3

In this example the ebullated bed reactor utilized above in Example 2was used. Molybdenum LIN-ALL(TM) available from OMG Americas, Inc. ofCleveland Ohio USA was mixed introduced into the hydroconversion zonealong with the hydrocarbon feed. The mixture of the hydrocarbon feed andthe molybdenum compound was carried out through the flush oil pump inthe fresh feed system. The concentration of molybdenum LIN-ALL wasapproximately 902 parts per million by weight which corresponds to 132parts per million metal. This stream represented 22.7% of the fresh feedinto the reactor. The hydrocarbon feed was mixed with the hydrogen feedgas and passed through the feed heater where the combined feed washeated to about 11° C. (20° F.) above the reactor temperature. Theresidence time of the combined feed in the feed heater is estimated tobe approximately 52 seconds at a total reactor pressure of 11,822 kPa(1700 psig) and about 40 seconds at about 1300 psig. The heated combinedfeed was then introduced into the hydroconversion zone of the reactor.As noted in Table 8 above, this method of introduction of the molybdenumLIN-ALL (TM) is considered injection method B. A sample of theproperties of the reaction product are given in above in Table 8. Itshould be noted that the values for the run were taken approximatelyseven days after the first introduction of molybdenum compound so as toallow the reaction to stabilize. In particular the present inventionallows for the operation of hydroconversion at pressures less than 1700psig and as shown above as low as 1300 psig. This is in contrast toconventional conditions which are typically 2500 psig or greater.

While the compositions and methods of this invention have been describedin terms of preferred embodiments, it will be apparent to those of skillin the art that variations may be applied to the process describedherein without departing from the concept, spirit and scope of theinvention. Other advantages of the present invention will be realized inthe practice of the present invention and appreciated by one of skill inthe art. All such similar substitutions and modifications apparent tothose skilled in the art are deemed to be within the spirit, scope andconcept of the invention as it is set out in the following claims.

What is claimed is:
 1. A process of catalytic hydroconversion of a heavyhydrocarbon oil containing a substantial portion of components having amatmospheric boiling point above about 565° C. (1059° F.) to give aproduct hydrocarbon oil containing a substantial portion of componentshaving a boiling point below about 565° C. (1050° F.), the processcomprising:mixing the heavy hydrocarbon oil with an oil solublemolybdenum compound, wherein the molybdenum compound has a firstdecomposition temperature of at least 222° C. (431° F.), to give amixture having from about 0.005 to about 0.050 weight percent molybdenumcompound, wherein said mixture consists essentially of the heavyhydrocarbon oil and the oil soluble molybdenum compound; introducing themixture into a hydroconversion zone, the hydroconversion zone being at atemperature from about 343° C. (650° F.) to about 454° C. (850° F.) anda total pressure from about 6996 kPa (1000 psig) to about 24,233 kPa(3500 psig) and containing heterogeneous catalyst, the catalystincluding a Group VIII non-noble metal oxide, and a Group VI-B metaloxide on an alumia or silica-alumina support; introducing a reactor feedgas into The hydroconversion zone, the reactor feed gas including amajority of hydrogen gas, the introducing being conducted at a rate from356.2 liters (H₂) / liters(oil) (2000 standard cubic feet (H₂) / Barrel(oil)) to about 1781.2 liters (H₂) / liters(oil) (10,000 standard cubicfeet (H₂) / Barrel (oil)); and, recovering the product hydrocarbon oilfrom the hydroconversion zone.
 2. The process of claim 1 wherein theGroup VIII non-noble metal oxide is nickel oxide and the Group VI-Bmetal oxide is molybdenum oxide.
 3. The process of claim 1 wherein thealumina or silica-alumina has a Total Surface Area from about 150 to 240m² /g, a Total Pore Volume (TPV) from 0.7 to 0.98 and a pore diameterdistribution such that no more than 20% of the TPV is present as primarymicropores having diameters no greater than 100 Å, at least about 34% ofthe TPV is present as secondary micropores having diameters from about100 to 200 Å, and from about 26% to 46% of the TPV is present asmacropores having diameters of at least 200 Å.
 4. The process of claim 1wherein the reactor feed gas contains at least 93% by volume of hydrogenand is substantially free of hydrogen sulfide.
 5. The process of claim 4wherein the reactor feed gas is introduced at a rate from about 356.2liters (H₂) / liters(oil) (2000 standard cubic feet (H₂) / Barrel (oil))to about 712.5 liters (H₂) /liters(oil) (4,000 standard cubic feet (H₂)/ Barrel (oil)).
 6. The process of claim 1 wherein the temperature ofthe hydroconversion zone is from about 371° C. (700° F.) to about 441°C. (825° F.) and the total pressure is from about 9065 kPa (1300 psig)to about 11,822 kPa (1700 psig).
 7. The process of claim 1 wherein themixing of the heavy hydrocarbon oil with an oil soluble molybdenumcompound includes mixing a first portion of the heavy hydrocarbon oilwith the soluble molybdenum compound to give a pre-feed mixture in whichthe concentration of molybdenum compound is from about 0.02 to about0.42 weight percent, and mixing said pre-feed mixture with additionalheavy hydrocarbon oil to give a reactor feed mixture having aconcentration of molybdenum compound from about 0.005 to about 0.050weight percent.
 8. The process of claim 1 wherein the recovered producthydrocarbon oil has an API gravity uplift of greater than 10 over theAPI gravity of the heavy hydrocarbon oil feed.
 9. The process of claim 1wherein the hydroconversion zone is an ebullated bed reactor and theintroducing of the mixture into the hydroconversion zone is conducted ata rate from about 0.08 to 1.5 m³ (oil) / m³ (reactor void volume)/hour.10. A method of hydrocracking a heavy whole petroleum crude oil havingat least 40 weight percent components boiling above about 565° C. (1050°F.) to give a processed crude oil containing a majority of componentsboiling below about 565° C. (1050° F.), the process comprising:mixingthe heavy whole petroleum crude with a oil soluble Group VI-B metalcompound, the metal compound having a first decomposition temperature ofat least 222° C. (431° F.), to give a reactor feed mixture having fromabout 0.005 to about 0.050 weight percent metal, wherein said reactorfeed mixture consists essentially of the heavy whole petroleum crude andthe oil soluble group VI-B metal compound; reacting the mixture and ahydrogen containing feed gas in an ebullated-bed reactor, the reactorbeing at a temperature from about 343° C. (650° F.) to about 454° C.(850° F.) and at a total pressure of no greater than about 13,201 kPa(1900 psig) and wherein the ebullated bed includes a supportedheterogeneous catalyst the supported heterogeneous catalyst comprising aGroup VIII non-noble metal oxide, a Group VI-B metal oxides no more than2 weight percent phosphorous oxide and an alumina or silica-aluminasupport; and, recovering the processed crude oil from the reactor. 11.The method of claim 10 wherein the Group VI-B metal compound in thereactor feed mixture is a molybdenum containing.
 12. The method of claim11 wherein the hydrogen containing feed gas includes a majority ofhydrogen gas and is substantially free of hydrogen sulfide, and whereinthe gas introduction is conducted at a rate from 356.2 liters (H₂) /liters(oil) (2000 standard cubic feet (H₂) / Barrel (oil)) to about1781.2 liters (H₂) / liters(oil) (10,000 standard cubic feet (H₂) /Barrel (oil)).
 13. The method of claim 12 wherein the mixing of theheavy whole petroleum crude oil with an oil soluble molybdenum compoundcomprises combining a first portion of the heavy whole petroleum crudeoil with the oil soluble molybdenum compound to give a pre-feed mixturein which the concentration of molybdenum compound is from about 0.020 toabout 0.420 weight percent, and mixing said pre-feed mixture withadditional heavy whole petroleum crude oil to give a reactor feedmixture having a concentration of molybdenum compound from about 0.005to about 0.050 weight percent.
 14. The method of claim 13 wherein thereactor feed mixture and the hydrogen containing feed gas are introducedinto the ebullated-bed reactor at a rate from about 0.08 to about 1.5 m³(oil)m³ (reactor void volume)/hour.
 15. The method of claim 14 whereinthe temperature of the reactor is from about 371° C. (700° F.) to about441° C. (825° F.) and the total pressure is from about 9065 kPa (1300psig) to about 11,822 kPa (1700 psig).
 16. The method of claim 15wherein the alumina or silica-alumina support has a Total Surface Area(TSA) of about 150 to 240 m² /g, and Total Pore Volume (TPV) from about0.7 to 0.98 and a pore diameter distribution such that no more than 20%of the TPV is present as primary micropores having diameters no greaterthan 100 Å, at least about 34% of the TPV is present as secondarymicropores having diameters from about 100 Å to about 200 Å, and fromabout 26% to about 46% of the TPV is present as macropores havingdiameters of at least 200 Å.
 17. The method of claim 16 furthercomprising combining the reactor feed mixture with hydrogen containingfeed gas at a pressure no more than about 205 kPa (15 psig) above thereactor pressure, pre-heating the pressurized reactor feed mixture in areactor feed heater to a temperature no greater than 11° C. (20° F.)above the reactor temperature immediately before introducing thepreheated, pressurized reactor feed into the reactor.
 18. The method ofclaim 17 wherein the recovered processed crude oil has an API gravityuplift of greater than 10 over the API gravity of the heavy wholepetroleum crude oil.
 19. The method of claim 10 wherein the processedcrude oil has a decreased amount of sediment in the portion of theprocessed heavy crude oil having a boiling point above about 343° C.(650° F.) as compared with the same product resulting from the processconducted without the molybdenum compound in the reactor feed mixture.